add log message if transformation runs into heap space shortage

[JohannaOtt]

If the transformation runs into heap space shortage, there is no feedback on that. The log is still displaying the current transformation task and the task manager's feedback is also not helpful. For the user there is no obvious way of finding out why the transformation is stuck. Simons idea: "Maybe something like this could be used or adapted: https://github.com/heroku/heroku-javaagent "